FYI, lots of useful break-shot advice (for both power and control) can be found in the following video:I've been experimenting this week with trying to finally get a B player (vs. D player) break.
bent my front elbow
look at cue ball last
work on centering my gravity
put more weight on my bridge hand
working on bringing my cue back more slowly.
struggling with pausing in between my back and forward swing
NV D.14 - Pool Break Technique Advice - from Vol-III of the Billiard University instructional DVD series
and much more can be found on the break technique advice resource page.
I hope it helps. Good luck!